Share Email Facebook Twitter LinkedIn To Modify the System Assigned to a Duct Select the duct segment. Click Duct tab Modify panel Modify Run . In the Modify Run dialog box, select System, and choose a new system from the drop-down list. Related Concepts About Duct System DefinitionsAbout Configuring Duct System DefinitionsAbout Modifying Duct Related Tasks To Modify Connected Objects Along a Duct Run